03/16/2004: "Studies on the effects of gay parenting on children"
Here is a fairly unbiased article about the research that has been done to determine what effects gay parents (good and bad) have on the children they are raising. At the end the author reveals that she is a proponent of gay marriage and although if I had to guess I would have guessed correctly about her biases before she revealed that, I have to appaud her for writing a fair article.
The basic point is that to date, we don't have any scientifically reliable studies to look at.
The thing that was written between the lines that I think is very important is that there is a large disagreement in our society about what the goal for our children is. While some think the goal is to make them more open to new ideas and leaving behind their traditions (including their religions at least in their current form) others think we need to be giving them a strong sense of right and wrong and moral and immoral while clinging to their traditions.
If we ever get more reliable data on what impact gay parents have on the children they raise, I think there is a large possibility that both sides will think the data supports their position.